Addition & subtraction with regrouping - 2nd grade

First I show with a visual model how, in adding two 3-digit numbers, we may get more than 10 tens, and those are then regrouped with the hundreds (we get an extra hundred). I soon tie the visual model in with the usual way of writing one number under the other. Later in the lesson I also show what happens when we add 3 numbers, and the sum of the tens exceeds 20. We also look at just a few mental math problems: 80 + 70, and how we can use that result to also solve 280 + 70 and 580 + 70. Lastly there is a PUZZLE to solve, once again, which makes Mathy so happy! See other 2nd grade math videos at